Tab sealant asphalt adhesive is conventionally applied to the front or upper surface of asphalt shingle material by print wheels which pick up hot liquid sealant asphalt from a supply trough and print it on the shingle material in broken-line patterns. The process is very sensitive to variations in the temperature of the sealant asphalt and to variations in the tension in the sheet of shingle material. This makes it difficult to accurately control the thickness or the amount of the tab sealant asphalt applied and results in inconsistent performance of the tab sealant asphalt when the shingles are installed on a roof of a house or other building structures. Conventionally the supply of hot liquid sealant asphalt is maintained at about 330.degree. to 350.degree. F. After application to the shingle material, the liquid tab sealant asphalt hardens and becomes an essentially void-free solid.